[Python-Dev] Enum Eccentricities

[Chris Lambacher]

On Sun, Sep 22, 2013 at 10:41 PM, Zero Piraeus <z at etiol.net> wrote:

> I may be misunderstanding the use case given in the issue,
>

To clarify the use case, since it is my bug, this is so that the enum
values are always available for comparison. The exact use case is in Django
templates where a value comes from the database. If you want to compare you
either have to use __class__ which I would say is a code smell, or you have
to provide the Enum class. The code we are using for this is open source
http://github.com/tindie/django-tidyenum. An example of how this will be
used in practice is:

    {% if object.state == object.state.completed %}
      some html
    {% endif %}


> but it seems
> to me that having to use
>
>     Color.red.__class__.blue
>
> (what is being complained about in the issue), while not exactly pretty,
> makes a lot more semantic sense than
>
>     Color.red.blue
>
> ... which is just bizarre.
>

Any more bizarre than any other class that has properties of it's own type?

      a = 0
      a.real.numerator.real.numerator

It is only weird because we are not used to seeing classes where the
properties are instances of the class. I am not a core developer, but I
have been programming in Python for more than 10 years, and I (and the
other similarly experienced developers I work with) found that not having
access to the class level properties was weird (yes I am aware that they
are not actually class level properties but everywhere else Enum works hard
to make it look like they are. See for instance the __dir__ method:
http://hg.python.org/cpython/file/ed011b0d7daf/Lib/enum.py#l242).

-Chris

-- 
Christopher Lambacher
chris at kateandchris.net
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